In recent years, continuous advancement of display technology results in increasing demands on display quality of displays (e.g. image resolution, color saturation) from users. However, in addition to high image resolution and high color saturation, displays capable of displaying stereoscopic images are also developed to satisfy the users' need of viewing real images.
The stereoscopic display technology that is developed more rapidly and completely is the spatial-multiplexed technology. In the spatial-multiplexed technology, a parallax barrier or a columnar lens is frequently used to form different viewing zones in the space for the viewer to receive different image information for his/her left eye and right eye, so as to achieve the stereoscopic effect. The technology of manufacturing barriers is more well-developed than the technology of manufacturing lenses, so the former is broadly applied in products.
Specifically, the parallax barrier is a periodic structure in which a transparent area and a non-transparent area alternately appear. The parallax barrier has an appropriate pitch and is laminated to an image cell in an appropriate distance. It is necessary for the image cell to simultaneously display images for the left and right eyes of the viewer which are alternately arranged. Thereby, after the image cell is laminated with the parallax barrier, the left eye of the viewer only sees the pixel displaying the left eye image, whereas the right eye of the viewer only sees the pixel displaying the right eye image. This indicates that due to a shading effect of the non-transparent area of the parallax barrier, the left eye is not able to see the pixel displaying right eye image. The same applies to the right eye. Therefore, when the image cell displays an image, the viewer is allowed to view a stereoscopic image at an appropriate location.
Taking a 2-view stereoscopic display for example, since the parallax barrier and pixel are both periodic structures, left and right image areas projected by the barrier periodically appear in the space. Namely, alternate left and right image areas are projected. Therefore, the left and right eyes of the viewer have to correspond to the left and right image areas to see a preferable stereoscopic image, or the left eye may see the right eye image, while the right eye may see the left eye image. This phenomenon is described as crosstalk. For example, when the viewer is located at a location corresponding to center of the display (i.e. center location), since the left eye falls in the center of the left eye image area and the right eye falls in the center of the right eye image area, the viewer is allowed to see a preferable stereoscopic image. Therefore, this viewing location is the appropriate viewing location that has minimal or hardly any crosstalk. However, when the viewer moves leftward or rightward from the center location, rendering the left eye falling in the center of the right eye image area and the right eye falling in the center of left eye image area, the viewer feels uncomfortable because of viewing an incorrect stereoscopic image. The phenomenon is described as pseudoscopy, and the area that leads the viewer to have a pseudoscopic vision is called dead zone. Crosstalk in the dead zone is much higher than the center area and causes discomfort of the viewer.
Since the stereoscopic display is limited by the so-called appropriate viewing location, making the viewer prone to feel fatigue when viewing, the willingness of the viewer to use the stereoscopic display is decreased. Therefore, reducing crosstalk to develop the stereoscopic display technology free of limitation on viewing location is one of the issues that the related industry has to work on.